Process for joining sheet metal or the like



Dec- 22, 1953 J. PFls'rERsHAMMER PROCESS FOR JOINING SHEET METAL 0R THE LIKE Filed March 16, 1949 Patented Dec. 22, 1953 H Massima4 Param y HELKE .y l 'fritocsssiijogormmesnssrfmal Josef Pfistershammer,

Application March 16, 1949, Serial No. 81,783

2 claims. l

My invention relates to a process for joining sheet metal, particularly for manufacturing cylindrical and conical tubes.

The usual manner of joining sheet metal by rivets requires rivet holes, which reduce 'the cross section and cause waste of material. The joining of sheets by flanging or welding is not always applicable, especially in the case of materials of high strength, such as certain alloy steels, high-carbon steels or refined aluminum alloys, whose low ductility makes them unsuitable for welding and fianging.

It is an object of my invention to overcome these disadvantages and diiiiculties.

According to the invention, I provide cuts at or near the edges of the sheets to be joined, so as to form identical tongues or groups of tongues. Subsequently the tongues of the two edge portions of material to be joined are bent off so that each tongue projects by about the thickness of the material. Then the tongues of each edge portion are pressed into the slots formed by the bending of the tongues of the adjoining edge portion. As a result, all tongues of the two edges can take up tensile stresses and shearing stresses with their whole cross sections.

These and other features of my invention will be apparent from the embodiments exemplified by the drawing, in which- Fig. 1 is a sectional view along the joint of two flat sheets, showing the sheets loosely placed together;

Fig. 2 is a. front view and Fig. 3 a sectional view of the same two sheets after they are rmly pressed against each other; Fig. 4 shows a sectional view of the sheets with the joint completed, and Fig. 5 is a top view of the sheets in the same intermediate stage as shown in Figs. 2 and 3; while Figs. 6- and 7 are a top View and a side view respectively of a butt joint also in an intermediate process stage similar to that of Figs. 2, 3 and 5.

In the joint, shown in Figs. 1 to 5, identical tongues I2 and I3, respectively, are cut from the two metal sheets I0 and II near the edges and bent as shown in Fig. 1. Each sheet is thus provided with slots I4 and I5, respectively, corresponding to the bent-oli tongues. For joining the sheets, they are placed together so that the tongues l2 of one sheet enters into respective slots I5 of the other sheet, and the tongues I3 of the other sheet enter into the slots I4 of the rst sheet. Each tongue I2 then lies adjacent to a tongue I 3 (Fig. l). Thereafter the two sheets are pressed together. As a result, the tongues penetrate through the slots like closelyfltting wedges (Figs. 2, 3). The length of the tongues slightly exceeds the thickness d of the sheets so that, when the sheets are joined together, the ends 9 of the tongues slightly protrude at both sides beyond the outside surface of the sheet (Fig. 9). Thereafter the protruding ends 9 are flattened under very high pressure so that the seam is sealed to be completely tight and to resist opening (Fig. 4).

This method is suitable for joining all kinds of materials and is not restricted to seams along the edges of the pieces of material. It is also suitable for particularly strong materials which resist deformation and are not suitable for being welded.

Figs. 6, 7 show two sheets I6, I1, which abut against each other along an edge h (without overlap). Both sheets are provided with tongues I8 and i9, respectively, which are all bent toward. the same side (downward in Fig. 6) in the same manner as described above with reference to tongues I2 (Figs. 1 to 3). The sheets I6, II are joined together by means of a strip 2D provided with two rows of tongues 2| and 22, which are also all bent toward the same side (upward in Fig. 6). The mutual engagement of the tongues and the sealing of the seam is eiected along the two rows exactly as described with reference to Figs. 1 to 5.

I claim:

l. The process of joining two sheet metal sheets, which comprises the steps of cutting into each sheet within its contour and near one of its edges a row of tongue-forming cuts, the cuts being substantially of the shape of three sides of a rectangle with the longest cut side opposite the tongue lfoot and transverse to said edge, the cuts in each sheet being alternately to the left and to the right of the tongue foot; bending the tongues of each sheet approximately at a right angle away from the sheet surface to be engaged by the other sheet thus forming respective openings adjacent to said tongues and of the same contour as said tongues, the tongues thus formed on each sheet projecting from the sheet a distance only slightly greater than the thickness of the adjacent sheet; overlapping the two sheets and placing the tongues of each sheet into the openings of the other sheet;` and applying upsetting force to the ends of the tongues in a direction substantially perpendicular to the sheet surface to rivet the tongues of each sheet in the openings of the other sheet.

2. The process of joining two sheet-metal parts, which comprises the steps of cutting into each part within its contour and near one of its edges a. row of tongue-forming cuts substantially of the shape of three sides of a rectangle, the cuts in each sheet part being alternately to the left and to the right of the tongue foot, and the height of the tongues being only slightly larger than the sheet thickness; bending the tongues of each part approximately at a. right angle away from the part surface tor be engaged by the other part thus forming respective openings adjacent to said tongues and of the same contour as said tongues; placing the two parts in mutually overlapping relation and pressing the tongues of each part into the openings of the other part; and applying upsetting force to the ends of the tongues in a direction substantially perpendicular to the sheet surface to rivet the tongues o! each part in the openings of the other part.

JOSEF PFISTERSHAMMER.

References Cited in the file oi. this patent UNITED STATES PATENTS Number Name Date 338,877 Ritchie Mar. 30, 1886 384,118 V.Bellinger June 5, 1888 518,767 Plecker Apr. 24, 1894 581,414 Cressler Apr. 27, 1897 1,034,483 Mills Aug. 6, 1912 2,009,568 Walker July 30, 1935 2,149,918 Komorous Mar. 7, 1939 2,251,926 Erb Aug. 12, 1941 

